The Institute for Electrical and Electronics Engineers (IEEE) has sanctioned a wireless standard for Ethernet access known as 802.11. The most common application for this standard is in wireless modems, although certainly other transmitter applications do exist. In most typical applications, the transmitter includes an antenna and transceiver combination that transmits at a power level that varies as a function of the process and temperature. In most operating environments, this variation does not matter. However, in instances where the 802.11 transmitter is a wireless modem incorporated into a laptop computer, or is otherwise battery powered, power consumption becomes an issue. There are times when applying a power control algorithm to the device could result in lower power consumption and thus prolong battery life. The concept of power control being applied to 802.11 is not new, but has not been successfully deployed to date.
In the cellular phone industry, the concept of power control has seen a more robust development. Specifically, some standards, such as Code Division Multiple Access (CDMA), rely extensively on the fact that each transmitter in a cell may vary output power such that the system may operate with greater efficiency and lower interference.
To date, power control algorithms have been implemented in the integrated circuit (IC) dedicated to the baseband processor. The baseband processor IC is distinct from the transceiver IC and the power amplifier IC. To give the designer the most flexibility in circuit design, the three ICs must work in harmony. Many circuit designers do not like to be restricted to choosing ICs from a single vendor or manufacturer. As a result, for best power control options, ICs from multiple vendors must work in harmony. All too often, for competition reasons, the ICs from multiple vendors do not work well together. As a result, the designer may incorporate components external to the ICs onto the circuit board to facilitate cooperation between the different ICs. The use of external components takes up precious space on the circuit board, increases component counts, and otherwise increases costs associated with the transmitter.
Thus, there remains a need for a power control mechanism that allows transmitter designers to simplify board designs while simultaneously being well suited for IEEE 802.11.